Targeting CD20 in the treatment of interstitial lung diseases related to connective tissue diseases: A systematic review

IntroductionThe effectiveness of CD20 targeting in connective tissue diseases (CTD) with lung involvement is controversial. This paper aims to review the current evidence about rituximab (RTX) use in CTD-related interstitial lung disease (ILD).MethodsWe performed a systematic review of papers published between January 2009 and May 2019. We included clinical trials, case/control studies and cohort studies. We excluded letters, case reports, case series, reviews, and full articles when not in English. The selected studies listed as primary or secondary outcome a variation in pulmonary function tests or in the scores used to radiologically stage lung involvement, in CTD-related ILD patients after RTX.ResultsOut of 1206 potentially eligible articles, 24 papers were selected: 3 retrospectively described cohorts of patients with different CTD, 14 dealt with systemic sclerosis (SSc)-related ILD, 5 with idiopathic inflammatory myopathies (IIMs)-related ILD, and 2 with Sjögren's Syndrome-related ILD.A direct comparison of the selected studies was hampered by their heterogeneity for outcomes, follow-up duration, the severity of lung involvement, and clinical features of study populations. However, an overall agreement existed concerning the effectiveness of RTX in the stabilization of lung disease, with some studies reporting an improvement of functional parameters from baseline. IIM-related ILD appeared more responsive than other CTD-related ILD to CD20 targeting.ConclusionRTX is a promising therapeutic tool in CTD-related ILD. This systematic review remarks the unmet need of multicenter prospective studies aiming to evaluate the effectiveness of RTX with adequate sample size and study design.     

Rituximab in refractory idiopathic inflammatory myopathies and antisynthetase syndrome: personal experience and review of the literature

In this paper, we report our experience with the use of rituximab (RTX) in the treatment of refractory idiopathic inflammatory myopathies (IIM) and review the literature on this topic. Six adult patients (5 female, 1 male) with active IIM, as defined by persistent proximal muscle weakness, elevated serum muscle enzymes, muscle magnetic resonance imaging, electromyographic and histological abnormalities, refractory to at least one immunosuppressant, including methotrexate, were treated with RTX (1,000 mg twice, 2 weeks apart). Patients were regularly followed up for serial assessment of muscle strength by manual muscle test 8 and creatine kinase serum levels. Three patients were affected with polymyositis (PM) and three with anti-t-RNA synthetase syndrome (ASS). A complete B-cell depletion was observed in all patients by 3 months after RTX. A significant clinical improvement was observed in 5 out of 6 cases 6 months after RTX. Only one mild infusion reaction and one case of Herpes zoster infection were observed. A review of the literature to find all the available cases of refractory patients affected with IIM from 1980 to 2012, using the PubMed database, was performed. We were able to find 27 papers, 18 on PM and dermatomyositis and 9 on ASS, including 88 and 40 patients, respectively. A significant improvement was observed in 80 % of patients overall and the drug was well tolerated in the majority of cases. In conclusion, RTX can be considered a therapeutic option in refractory IIM.     

Efficacy and safety of intravenous and subcutaneous immunoglobulin therapy in idiopathic inflammatory myopathy: A systematic review and meta-analysis

ObjectiveTo perform a systematic review and meta-analysis on the efficacy and safety of intravenous (IVIg) and subcutaneous (SCIg) immunoglobulin (Ig) therapy in the treatment of idiopathic inflammatory myopathy (IIM) and juvenile dermatomyositis (JDM).MethodsPubMed, Embase and SCOPUS were searched to identify studies on Ig therapy in patients with IIM and/or JDM (2010?2020). Outcome measures were complete response (CR) or partial response (PR) in terms of muscle power and extramuscular disease activity measures on the International Myositis Assessment and Clinical Studies Group (IMACS) core set domains.ResultsTwenty-nine studies were included (n = 576, 544 IIM, 32 JDM). Muscle power PR with pooled Ig therapy was 88.5% (95% confidence interval (CI): 80.6–93.5, n = 499) and PR with SCIg treatment was 96.61% (95% CI: 87.43–99.15, n = 59). Pooled PR with first-line use of IVIg was 77.07% (95% CI: 61.25–92.89, n = 80). Overall, mean time to response was 2.9 months (95% CI: 1.9–4.1). Relapse was seen in 22.76% (95% CI: 14.9–33). Studies on cutaneous disease activity and dysphagia showed significant treatment responses. Glucocorticoid and immunosuppressant sparing effect was seen in 40.9% (95% CI: 20–61.7) and 42.2% (95% CI: 20.4–64.1) respectively. Ig therapy was generally safe with low risk of infection (1.37%, 95% CI: 0.1–2.6).ConclusionsAdd-on Ig therapy improves muscle strength in patients with refractory IIM, but evidence on Ig therapy in new-onset disease and extramuscular disease activity is uncertain.     

Edematous myositis: a clinical presentation first suggesting dermatomyositis diagnosis

Aims: Edema of the limbs is uncommon in idiopathic inflammatory myopathies (IIM). The few reported cases have been associated with severe and refractory dermatomyositis (DM), sometimes in association with cancers. We aimed to determine if edematous myositis is a homogeneous subtype based on clinical, serological and pathological features. Methods: This is a retrospective observational study performed between 2008 and 2015 in the French national referral center for myositis. All adult patients with an inflammatory muscle biopsy and upper limbs edema were included as well as IIM cases without limb edema as controls. Clinical, biological and pathological features were collected. Results: Seventeen edematous myositis were included and compared to 174 IIM without edema, including 50 DM controls. Edema was the first manifestation in 23% of patients. Muscle weakness was severe and symmetric, 71% of patients presented dysphagia and a restrictive ventilatory pattern was found in 40%. Fifty‐two percent of patients had a typical DM skin rash and 23% had cancer within 3 years of diagnosing myositis. Fifty‐three percent of patients presented a myositis specific antibody and only DM‐specific antibodies were detected. Classic pathological DM features (perifascicular atrophy, perifascicular/perimysial perivascular inflammation) were uncommon but capillary C5b‐9 deposition and MxA expression were seen in 79% and 73% of cases, respectively. A perimysial edema was found in 82% of cases. Seventeen percent of patients died (median follow up of 18 months). Edematous myositis demonstrated more marked capillary C5b‐9 deposition compared to IIM controls. There was no clinical, biological or pathological difference with DM controls except for limb edema. Conclusion: Our study underlines that limb edema could be a symptom of IIM and that edematous myositis are mostly DM. The vasculopathy seems to play a key role in its pathophysiology. Limb edema associated with muscle impairment should suggest the diagnosis of DM in clinical settings.     

Autoantibodies specifically detected in patients with polymyositis/dermatomyositis]

Polymyositis/Dermatomyositis (PM/DM) is a chronic inflammatory disorder that culminates in injury to the skin and muscle and, sometimes, is accompanied by interstitial lung disease (ILD). A number of autoantibodies are associated with myositis, including those specific for aminoacyl-tRNA synthetase (anti-ARS), signal recognition particle (anti-SRP), and Mi-2. These autoantibodies have proven to be useful in the diagnosis and classification of the diseases and are predictive of prognosis. It has been known that certain patients may have typical DM skin manifestations without clinical evidence of myositis for at least 2 years (Clinically Amyopathic DM; C-ADM). Although classical myositis-related antibodies are well known, specificities related to C-ADM have not been examined in detail. Therefore, we have examined sera from 15 Japanese patients with C-ADM to identify additional autoantibodies associated with this disease. Eight sera of C-ADM patient recognized a polypeptide of approximately 140 kDa and we named this new antibody specificity anti-CADM-140. Anti-CADM-140 antibodies were detected in 8 of 42 patients with DM, but not in patients with other connective tissue diseases or idiopathic pulmonary fibrosis. It is noteworthy that DM patients with anti-CADM-140 had significantly more rapidly progressive ILD when compared to patients without anti-CADM-140 (50% vs 6%, P=0.008). Further studies of the pathogenicity of these autoantibodies specificity may provide insight into the pathogenic mechanisms of PM/DM accompanied by rapidly progressive ILD.     

特发性炎性肌病的临床病理分析

目的 探讨特发性炎性肌病（IIM）的临床特点、病理及治疗结果.方法 回顾性分析162例特发性炎性肌病的临床表现、实验室检查及治疗效果.结果 162例患者中,男性65例、女97例.诊断为单纯性多发性肌炎（PM）54例;单纯性皮肌炎（DM）78例;伴有其他结缔组织病17例;伴恶性肿瘤13例.临床特点以近端肌无力为首发症状者多见,以肌痛者次之.皮肌炎伴发肿瘤10例、多发性肌炎伴发肿瘤3例.有肌电图记录122例中,有异常者114例（93.44%）,无异常者8例.实验室检查以红细胞沉降率增快和肌酸激酶升高最为敏感.98例接受病理学检查,均符合皮肌炎或多发性肌炎的病理特点.其中有3例除血管周围有炎性细胞浸润外,还可见到脂肪细胞、泡沫细胞,符合脂质沉积性肌病的诊断.主要应用糖皮质激素、或甲泼尼龙冲击治疗或联合应用免疫抑制剂（环磷酰胺、硫唑嘌呤）.病情好转或痊愈出院者137例（82.09%）,治疗无改善及自动出院者6例（4.48%）,死亡19例（11.73%）.脂质沉积性肌病患者皮质激素治疗效果好,肌力恢复到5级或接近到5级.结论 特发性炎性肌病男女发病比率为1：1.49,女性略多.以肌无力为首发症状占大多数,表现为上楼无力,以肌痛者次之.皮肌炎更易伴肿瘤发生.肌电图是诊断皮肌炎或多发性肌炎的重要检查手段,阳性率占93.4%,但仍要以临床特点及病理检查为主要诊断依据.如果病理检查见到脂肪细胞、泡沫细胞时应诊断“脂质沉积性肌病”而不应该诊断PM或DM,并以皮质激素效果好.临床和病理科医师应加强对脂质沉积性肌病的认识,提高诊断率.     

Biologic drugs in the treatment of polyarteritis nodosa and deficit of adenosine deaminase 2: A narrative review

Polyarteritis nodosa (PAN) is a medium vessels vasculitis variously involving different organs and systems, sometimes with an aggressive course, leading to death or disability in a significant number of cases. First-line treatment usually relies on steroids and classical immunosuppressants, but a growing number of case reports and small case series shows the potential role of biologic drugs, mostly anti-tumor necrosis factor (TNF)-α agents, in inducing and maintaining remission in patients affected by PAN. Similarly, the recently described autoinflammatory disease named deficit of adenosine deaminase 2 (DADA2), considered by several experts as a more precocious and aggressive variant of PAN, seems to respond to a prompt treatment with TNF-α inhibitors. The aim of this review is to collect all existing evidences about the use of biologic drugs in PAN and DADA2. Fifty-one articles published during the last 15 years were retrieved, including 58 and 76 patients affected by PAN and DADA2, respectively, and treated with biologic drugs. The majority of subjects was treated with TNF-α inhibitors, whose effectiveness was reported in the treatment of such difficult-to-manage diseases, particularly in DADA2. Among the other biologic drugs, Tocilizumab was successfully employed in some subjects affected by PAN who did not respond to TNF-α inhibitors, while Rituximab did not give substantial benefits neither in PAN nor in DADA2. Only few data exist about the role of Janus-kinase inhibitors and anti-IL1 agents.This study provides the first comprehensive assessment of biologic agents in both PAN and DADA2, with encouraging results especially in the context of TNF-α inhibitors. Nevertheless, due to the lack of prospective, randomized, case control studies, further efforts should be made in order to fully elucidate the role of these drugs in such rare and life-threatening conditions.     

Infection risk in patients undergoing treatment for inflammatory arthritis: non-biologics versus biologics

ABSTRACT

Introduction: Despite the therapeutic effectiveness of biologics targeting immune cells or cytokines in patients with inflammatory arthritis, which reflects their pathogenic roles, an increased infection risk is observed in those undergoing biological treatment. However, there are limited data regarding the comparison of infection risks in inflammatory arthritis patients treated with non-biologics (csDMARDs), biologics (bDMARDs), including tumor necrosis factor (TNF) inhibitors and non-TNF inhibitors, or targeted synthetic (ts)DMARDs.

Areas covered: Through a review of English-language literature as of 30 June 2019, we focus on the existing evidence on the risk of infections caused by bacteria, Mycobacterium tuberculosis, and hepatitis virus in inflammatory arthritis patients undergoing treatment with csDMARDs, bDMARDs, or tsDMARDs.

Expert opinion: While the risks of bacterial and mycobacterial infection are increased in arthritis patients treated with csDMARDs, the risks are further higher in those receiving bDMARDs therapy, particularly TNF inhibitors. Regarding HBV infection, antiviral therapy may effectively prevent HBV reactivation in patients receiving bDMARDs, especially rituximab. However, more data are needed to establish effective preventive strategies for HBsAg-negative/HBcAb-positive patients. It seems safe to use cyclosporine and TNF inhibitors in patients with HCV infection, while those undergoing rituximab therapies should be frequently monitored for HCV activity.

Abbreviations: ABT: abatacept; ADA: adalimumab; AS: ankylosing spondylitis; bDMARDs: biologic disease-modifying anti-rheumatic drugs; CKD: chronic kidney disease; COPD: chronic obstructive pulmonary disease; CS: corticosteroids; CsA: cyclosporine A; csDMARDs: conventional synthetic disease-modifying anti-rheumatic drugs; CZP: certolizumab; DAAs: direct-acting antiviral agents; DM: diabetes mellitus; DOT: directly observed therapy; EIN: Emerging Infections Network; ETN: etanercept; GOL: golimumab; GPRD: General Practice Research Database; HBV: hepatitis B virus; HBVr: HBV reactivation; HBsAg+: HBsAg-positive; HBsAg-/anti-HBc+: HBsAg-negative anti-HBc antibodies-positive; HCV: hepatitis C virus; HCQ: hydroxychloroquine: IFX: infliximab; IL-6: interleukin-6; JAK: Janus kinase; LEF: leflunomide; LTBI: latent tuberculosis infection; mAb: monoclonal antibody; MTX: methotrexate; OR: odds ratio; PsA: psoriatic arthritis; PMS: post-marketing surveillance; RA: rheumatoid arthritis; TNF: tumor necrosis factor; TNFi: tumor necrosis factor inhibitor; SCK: secukinumab; SSZ: sulfasalazine; TOZ: tocilizumab; RCT: randomized controlled trial; RR: relative risk; RTX: rituximab; 3HP: 3-month once-weekly isoniazid plus rifapentine; TB: tuberculosis; tsDMARDs: targeted synthetic disease-modifying anti-rheumatic drugs; UTK: ustekinumab; WHO: World Health Organization     

Polymyositis/dermatomyositis and interstitial lung disease: a new therapeutic approach with T-cell-specific immunosuppressants

Interstitial lung disease (ILD) is a common complication of polymyositis (PM) and dermatomyositis (DM), and accounts for a significant proportion of their morbidity and mortality because of the resistance to therapeutic agents including corticosteroids. Its pathogenic mechanism is not known, but several studies have provided findings implicating that T-cells, especially activated CD8+ cells, may play essential roles, and thus could be therapeutic targets in this disease. To test this hypothesis, we began clinical investigation of the efficacy of T-cell-specific immunosuppressants, cyclosporine (CsA) and FK506, in PM/DM patients with ILD. In our retrospective nationwide multi-center study compiling a total of 53 patients, a combination of CsA and corticosteroids resulted in favorable early and long-term outcome in the majority of patients except for DM patients with acute ILD. In this subset, those who received the combination as an initial therapy had better survival than those who initially received corticosteroids alone. FK506 has a similar mode of action but is up to 100-fold more potent than CsA in vitro, and has been used in more refractory ILD cases. We next reviewed 5 PM/DM patients with ILD who failed on various immunosuppressants including CsA and were subsequently treated with FK506 in our hospital, and found that 3 improved promptly, 1 gradually and steadily, and another case responded slowly after prednisolone dose was increased. None developed adverse effects. In summary, these T-cell targeted therapies have a potential to be the cornerstone of the treatment for ILD in PM/DM patients. The combination therapy with CsA and corticosteroids may be efficacious especially when used early. FK506 may be advantageous even in refractory cases to CsA. These findings indicate that further investigation is warranted. Currently, prospective investigation of FK506 is underway.     

Polymyositis/dermatomyositis and interstitial lung disease: A new therapeutic approach with T-cell-specific immunosuppressants

Interstitial lung disease (ILD) is a common complication of polymyositis (PM) and dermatomyositis (DM), and accounts for a significant proportion of their morbidity and mortality because of the resistance to therapeutic agents including corticosteroids. Its pathogenic mechanism is not known, but several studies have provided findings implicating that T-cells, especially activated CD8+ cells, may play essential roles, and thus could be therapeutic targets in this disease. To test this hypothesis, we began clinical investigation of the efficacy of T-cell-specific immunosuppressants, cyclosporine (CsA) and FK506, in PM/DM patients with ILD.

In our retrospective nationwide multi-center study compiling a total of 53 patients, a combination of CsA and corticosteroids resulted in favorable early and long-term outcome in the majority of patients except for DM patients with acute ILD. In this subset, those who received the combination as an initial therapy had better survival than those who initially received corticosteroids alone. FK506 has a similar mode of action but is up to 100-fold more potent than CsA in vitro, and has been used in more refractory ILD cases. We next reviewed 5 PM/DM patients with ILD who failed on various immunosuppressants including CsA and were subsequently treated with FK506 in our hospital, and found that 3 improved promptly, 1 gradually and steadily, and another case responded slowly after prednisolone dose was increased. None developed adverse effects.

In summary, these T-cell targeted therapies have a potential to be the cornerstone of the treatment for ILD in PM/DM patients. The combination therapy with CsA and corticosteroids may be efficacious especially when used early. FK506 may be advantageous even in refractory cases to CsA. These findings indicate that further investigation is warranted. Currently, prospective investigation of FK506 is underway.     

Efficacy of low-dose methotrexate in rheumatoid arthritis

Twenty-eight patients with refractory rheumatoid arthritis completed a randomized 24-week double-blind crossover trial comparing oral methotrexate (2.5 to 5 mg every 12 hours for three doses weekly) with placebo. The methotrexate group had significant reductions (P less than 0.01 as compared with the placebo group) in the number of tender or painful joints, the duration of morning stiffness, and disease activity according to physician and patient assessments at the 12-week crossover visit; reductions in the number of swollen joints (P less than 0.05) and 15-m walking time (P less than 0.03) also occurred. These variables, as well as the grip strength and erythrocyte sedimentation rate, showed significant (P less than 0.01) improvement at 24 weeks in the population crossed over to methotrexate. A significantly increased frequency (P less than 0.03) of the HLA-DR2 haplotype occurred in the eight patients with the most substantial response to methotrexate. Adverse reactions during methotrexate therapy included transaminase elevation (21 per cent), nausea (18 per cent), and diarrhea (12 per cent); one patient was withdrawn from the trial because of diarrhea. One patient died while receiving the placebo. Methotrexate did not affect measures of humoral or cellular immunity. We conclude that this trial provides evidence of the short-term efficacy of methotrexate in rheumatoid arthritis, but the mechanism of action is unknown. Longer trials will be required to determine the ultimate safety and effectiveness of this drug.     

Functional and isokinetic assessment of muscle strength in patients with idiopathic inflammatory myopathies

OBJECTIVE: To assess muscle strength in patients with idiopathic inflammatory myopathies (IIM) using neuromuscular scales and isokinetic testing. METHODS: Muscle function was evaluated in 27 IIM patients being followed at the Rheumatology Unit of the University of Pisa using: (i) a modified version of the grading system used to assess Duchenne dystrophy, (ii) the four-stage grading system of Henriksson and Sandstedt, (iii) an isokinetic muscle strength test (Kin Com, Chatanooga) and (iv) the Health Assessment Questionnaire (HAQ). RESULTS: The neuromuscular scales showed normal or only mildly impaired muscle strength in 60% (Duchenne scale) and 80% (Henriksson and Sandstedt scale) of the patients, respectively, whereas isokinetic testing detected moderate to severe reductions in muscle strength in almost 70% of the patients. No correlations were observed between muscle strength and disease activity, therapy, age at evaluation and disease duration. There was a correlation between the results of the HAQ and neuromuscular testing, but not the isokinetic test. CONCLUSIONS: Although less easy and more expensive to administer, isokinetic testing appears to be a more sensitive instrument than the standard neuromuscular tests for assessing muscle function in IIM patients. In particular, it can detect small reductions in muscle strength.     

Efficacy and safety of abatacept in interstitial lung disease of rheumatoid arthritis: A systematic literature review

BackgroundInterstitial lung disease (ILD) is a serious complication that represents the second leading cause of death in patients with rheumatoid arthritis (RA). Treatment of RA-ILD remains controversial. The absence of randomized clinical trials and specific ACR or EULAR therapeutic guidelines makes it difficult to establish solid therapeutic recommendations on this issue. In this scenario, real-world data is especially valuable.ObjectiveTo review the literature evidence on the efficacy and safety of abatacept (ABA) for the treatment of rheumatoid arthritis (RA) with associated interstitial lung disease (ILD), given its clinical relevance and the lack of consensus on its therapeutic management.MethodsPUBMED and EMBASE were searched from the date of approval of ABA to the end of 2020 using a combination of RA, ILD and ABA terms following PRISMA guidelines. Identified studies were evaluated by two independent investigators.ResultsNine original studies (1 case series and 8 observational studies) were selected for inclusion in the systematic review. No randomized trial or meta-analysis were identified. The mean age of patients ranged from 61.2 to 75 years and the mean RA duration varied from 7.4 to 18 years. Subcutaneous ABA (74.5%–91%) predominated in combination with conventional synthetic DMARDs (csDMARDs) (58%–75%), and it was used as first-line biologic agent in 22.8%–64.9% of the patients. The mean course of ILD ranged from 1 to 6.7 years, being usual and nonspecific interstitial pneumonia the most frequent patterns. Improvement or stabilization of ILD imaging (76.6%–92.7%) and FVC or DLCO (>85%) was described after a mean follow-up of 17.4–47.8 months, regardless of the pattern of lung involvement, being more remarkable in patients with shorter evolution of ILD. ABA led to significantly lower ILD worsening rates than TNF inhibitors (TNFi) and was associated with a 90% reduction in the relative risk of deterioration of ILD at 24 months of follow-up compared to TNFi and csDMARDs. Combination with methotrexate may have a corticoid-sparing effect. No unexpected adverse events were identified.ConclusionsCurrent evidence suggests that ABA may be a plausible alternative to treat RA patients with ILD. It would be highly desirable to develop prospective randomized controlled studies to confirm these findings.     

Functional and isokinetic assessment of muscle strength in patients with idiopathic inflammatory myopathies

Objective: To assess muscle strength in patients with idiopathic inflammatory myopathies (IIM) using neuromuscular scales and isokinetic testing.

Methods: Muscle function was evaluated in 27 IIM patients being followed at the Rheumatology Unit of the University of Pisa using: (i) a modified version of the grading system used to assess Duchenne dystrophy, (ii) the four-stage grading system of Henriksson and Sandstedt, (iii) an isokinetic muscle strength test (Kin Com, Chatanooga) and (iv) the Health Assessment Questionnaire (HAQ).

Results: The neuromuscular scales showed normal or only mildly impaired muscle strength in 60% (Duchenne scale) and 80% (Henriksson and Sandstedt scale) of the patients, respectively, whereas isokinetic testing detected moderate to severe reductions in muscle strength in almost 70% of the patients. No correlations were observed between muscle strength and disease activity, therapy, age at evaluation and disease duration. There was a correlation between the results of the HAQ and neuromuscular testing, but not the isokinetic test.

Conclusions: Although less easy and more expensive to administer, isokinetic testing appears to be a more sensitive instrument than the standard neuromuscular tests for assessing muscle function in IIM patients. In particular, it can detect small reductions in muscle strength.     

Autoantibodies in idiopathic inflammatory myopathies: Clinical associations and laboratory evaluation by mono- and multispecific immunoassays

Idiopathic inflammatory myopathies (IIM) are a group of diseases characterized by immune-mediated muscular lesions that may be associated with extra-muscular manifestations involving skin, lungs, heart or joints. Four main groups of IIM can be distinguished: dermatomyositis (DM), overlap myositis including mainly anti-synthetase syndrome (ASS), immune mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). Myositis-specific autoantibodies (MSA) are increasingly recognized as valuable tools for diagnosis, classification and prognosis of IIM. For example, ASS is associated with anti-aminoacyl tRNA synthetase antibodies (anti-Jo-1, PL-7, PL-12, …), IMNM with anti-SRP and anti-HMGCR; IBM with anti-cytosolic 5’nucleotidase 1A (cN1A), and DM with anti-Mi-2, anti-MDA-5, anti-TIF-1γ, anti-NXP-2 and anti-SAE. Moreover, anti-MDA-5 is associated with amyopathic myositis and interstitial lung disease and anti-TIF-1γ and anti-NXP-2 with juvenile DM as well as malignancy in patients >40?years. Most MSA have initially been discovered by immunoprecipitation. In routine laboratories, however, MSA are screened for by indirect immunofluorescence and identified by (automated) monospecific immunoassays or by multispecific immunoassays (mainly line/dot immunoassays). Validation of these (multispecific) assays is a challenge as the antibodies are rare and the assays diverse. In this review, we give an overview of the (clinical) performance characteristics of monospecific assays as well as of multispecific assays for detection of MSA. Although most assays are clinically useful, there are differences between techniques and between manufacturers. We discuss that efforts are needed to harmonize and standardize detection of MSA.     

Anti-Jo-1 antibodies

Anti-Jo-1 antibody is a myositis specific autoantibody most commonly found in patients with idiopathic inflammatory myopathies (IIM). This antibody is directed against the histidyl-tRNA synthetase which catalyses the binding of the histidine to its cognate tRNA during protein synthesis. It can be considered a specific marker of IIM, predominantly found in 20-30% of patients with PM and in the 60-70% of those with interstitial pulmonary fibrosis. These antibodies are also found in DM, although less frequently than in PM, and are rare in children with PM or DM and in other connective tissue diseases.ELISA, CIE and immunoblotting are highly specific and sensitive techniques for testing anti-Jo-1 antibodies. The detection of this antibody is particularly useful in diagnosis and classification of IIM. Moreover, anti-Jo-1 serum levels strongly correlate with disease activity representing a good marker for disease monitoring.     

MRI and muscle imaging for idiopathic inflammatory myopathies

Although idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases nearly all patients display muscle inflammation. Originally, muscle biopsy was considered as the gold standard for IIM diagnosis. The development of muscle imaging led to revisiting not only the IIM diagnosis strategy but also the patients’ follow‐up. Different techniques have been tested or are in development for IIM including positron emission tomography, ultrasound imaging, ultrasound shear wave elastography, though magnetic resonance imaging (MRI) remains the most widely used technique in routine. Whereas guidelines on muscle imaging in myositis are lacking here we reviewed the relevance of muscle imaging for both diagnosis and myositis patients’ follow‐up. We propose recommendations about when and how to perform MRI on myositis patients, and we describe new techniques that are under development.